What is the implication of a mandatory rule in the NEC?

A mandatory rule in the National Electrical Code (NEC) signifies that it must be adhered to without exception. This means that all individuals and entities subject to the NEC are required to follow these rules in order to ensure safety and compliance with established standards. Mandatory rules are designed to protect public safety and welfare by providing clear, enforceable guidelines that must be implemented in electrical installations and practices. Noncompliance with mandatory rules may result in legal consequences, unsafe conditions, or failures in system performance.

In contrast, other types of rules in the NEC may offer flexibility, such as suggestions or modifications, which could mislead the interpretation of mandatory rules if understood incorrectly.